diff --git a/layout/style/nsCSSProperty.h b/layout/style/nsCSSProperty.h
index db34d2d8522b..f261283ef7dc 100644
--- a/layout/style/nsCSSProperty.h
+++ b/layout/style/nsCSSProperty.h
@@ -34,6 +34,9 @@
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */
+
+/* enum types for CSS properties and their values */
+ 
 #ifndef nsCSSProperty_h___
 #define nsCSSProperty_h___